U.S. Pat. No. 4,098,956 to Blickensdorfer et al discloses a process for making spectrally selective solar absorbers by depositing layers of metal or carbides, including titanium, wherein oxides, suboxides, or nitrides can be produced using the appropriate atmosphere of oxygen or nitrogen with argon during sputtering. In one embodiment a subnitride of the metal is produced. Pendse U.S. Pat. No. 3,503,787 is concerned with making refractory aluminum nitride coatings by plasma spraying. Titanium nitride is formed by the use of nitrogen in the plasma. Wakefield U.S. Pat. No. 3,912,461 is directed to the sputtering of titanium carbonate onto a substrate to produce a hard, wear-resistant surface. None of these patents is concerned with providing metal nitrides in the interfacial region between a substrate and refractory coating.